Statistical analysis
Categorical data are presented as frequencies and percentages, and quantitative data are provided as median and interquartile range (IQR). Demographic, clinical and outcome variables were compared between the two groups of patients, using Fisher’s exact test for qualitative variables and Mann-Whitney U test for quantitative variables. The comparisons were carried out for all patients and by age group (younger than 1 year, 1 to 9 years and 10 years or older).
We estimated the crude and adjusted odds ratio and 95% confidence intervals (CI) for death and invasive mechanical ventilation using logistic regression. The final model included age a priori; other variables (sex, nutritional status, comorbidities) were included based on reverse stepwise regression (i.e., stopping rule Wald test <0.20). All analyses were performed using STATA 15 statistical package. (College Station, TX, USA: StataCorp).